Although I'm using the bottom link for my tiller, it looks like the hook-up for a Brinely or scrach built hitch would be the same. The two bottom arms attach to the two pivot pins on the bottom of the axle, the vertical lift arm on the right side hooks to the horizontal bar that extends rearward from the deck lift assembly. What ever you use for the cross brace for the bottom arms has to be in a position to clear the hitch plate (if you have one) on the rear end.
I would just measure twice, make a mock-up out of some sheet metal, then cut and weld 'er up. "Better stout, than out".